If I didn't mention I had a stutter, I don't think I would have passed any of the interviews I had. I try to turn it into a good thing in my answers - how I have a stutter has made me to want to work for this company for their open and inclusive culture and way of working. Also how I still try and do presentations and get to know people to throw myself into it and not let it bother me. In terms of stuttering on the interview itself, I'd mention it at the start before talking (say it with a smile) and just be patient. Talk slowly, don't rush answers. You'll be fine :) Good luck!